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(No Model.) 3 Sheets-Sheet 1.

R. G. STANBROUGH.

DENTAL ENGINE.

N0 520,867. Patented June 5, 1894.

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H G UR 0N M. BN E L m N .E D R (No Model.)

,867. Patented June 5, 1894.

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ATENI DENTAL ENGINE.

SPECIFICATION forming part of Letters Patent No. 520,867, dated June5,1894.

Application filed December 2. 1892. Serial No. 453,818. (No model.)

To aZZ whom it may concern:

Be it known that 1, Burns G. STANBRoUcH,

a citizen of the United States, and a resident.

of New York, in the county of New York and State of New York, haveinvented certain new and useful Improvements in Dental Engines, of whichthe following is a specification.

The object of this invention is to provide means for securing a constantspeed of the tool shaft of a dental engine attached to or carried by avertically adjustable operating chair, without restricting the latitudeof movement of such shaft and chair.

A further object of the invention is to provide means for reducing thespeed or stopping the engine at pleasure without diminishing the speedof the motor.

To these ends my said invention consists in a dental engine movablysecured to a vertically movable operating chair, a driving bolt, thetension upon which is controlled by a weight or analogous device ridingthereon, and means for raising said weight away from the belt to reducethe tension, allas hereinafter more particularly described and pointedout in the claims.

In the accompanying drawings illustrating my invention, in the severalviews of which like parts are similarly designated, Figure 1, is anelevation showing part of the operating chair, and my device in positionfor use. Fig. 2, is a detail of the pivoted arm to which the engine issecured. Fig. 3, is a side elevation showing the'motor, a portion of thedental engine, and the tension device, with their connections. Fig. 4,is asimilar front elevation; and Figs. 5, 6, and 7, are details of thepulleys constituting a part of the tension device, and under which thedriving belt passes.

A, is the operating chair, capable of vertical movement throughrthefoot-lever A, in the ordinary manner, and having pivoted beneath itsseat the usual arm B for the tool box or table, carrying thehorizontalarm B, to which said tool-box or table is attached; and carrying alsothe vertically projecting tubular standard G, within which the toolshaft rests, as shown particularly in Fig. 3. Located beneath said toolshaft, and surrounding the standard 0, is the loose collar D, carryingthe horizontal hub or shaft D, to the outer ends of which the twinpulleys E, E, are journaled.

Said hub also, has the upper eye or perforated ing a, for a purpose tobe hereinafter explained, and the lower eye a, to which the Weight F, isattached through the link F.

Secured to the ceiling, or other suitable support, is the swivel yoke G,carrying the twin pulleys H, H, and the lower auxiliary pulley H.

I, is the driving belt passing under the driving wheel J, on the motorJ, thence over twin pulleys H, H, in swivel yoke Gr, thence under twinpulleys E, E, and thence up over driving wheel K, on the said tool shaftof the dental engine.

The operation of my invention as so far explained, will be apparent fromthe foregoing. When the operating chair is lowered, it carries downwardwith it the pivoted arm B, standard 0, and the tool shaft; and thecollar D, carrying the weight F, and twin pulleys E, E, riding upon thebelt I, also drop a corresponding distance, maintaining a constant andeven tension upon said belt, and rotating the'engine at a uniform speed.When the chair is raised, the pulleys and weight are also raised, andthe same results are attained; as they are also upon swinging the chairon its axis, or upon partially rotating the pivoted arm B, and standard0, or upon moving the tool shaft relative to its said standard; thecollar D,being sufficiently loose to slide upon the said standard 0',and permit the weight to be constantly exerted upon the driving belt.

To diminish or entirely release the tension upon the driving belt, I,and thereby reduce the speed of the engine or stop the same altogether,I attach to the eye a, on the hub D, the cord L, and pass the same upover the pulley H in yoke G, and thence down and under the pulleyM,which'is preferably pivotallysecured to the floor, and attach the otherend of said cord to one end of the lever .N, which, as

shown in Figs. 1 and 3, is fulcrumed at O, and is preferably provided atits free end with the spring P. It will be apparent that when theoperator depresses the free end of lever N, against the tension ofspring P, he will raise the collar D, on standard 0, and with it theweight F, and twin pulleys E, E, away from the driving belt I, thusremoving the tension to any desired degree. If preferred, this latterpart of my invention may be omitted and the speed of the deviceregulated and varied by means of a switch, operated either by hand or byfoot, in any ordinary and wellknown manner.

5 It will be seen that great latitude of movement 1s acquired by the useof my invention, as the chair may be swung on its axis in eitherdirection; the pivot arm B, and standard G, is capable of movementindependent of said chair, and the tool shaft resting in the top ofstandard (3, is also movable with reference to the rest of the device;the driving belt and tension device adapting themselves to the var1ouspositions through swivel yoke G, loose I 5 collar D, and the swivelpulley M. It will also be obvious that many structural changes andmodifications may be made in the device and connections, withoutdeparting from the principle of the invention, and involving merely theskill of a mechanic.

That I claim as my invention, and desire to secure by Letters Patent,is-

1. In a dental engine, a tool shaft mounted on a standard adapted to bepivoted to a ver- 2 5 tically and pivotally movable operating chair,means for rotating said shaft through a belt, and means for maintainingconstant tension upon such belt at the varying heights of the chair,substantially as described.

2. In a dental engine,a tool shaft mounted upon a standard which isadapted to be arranged upon avertically adjustable operating chair, abelt passingabout a driven wheel, overhead twin pulleys about which thebelt 5 thence passes, twin pulleys arranged below the tool shaft andreceiving the belt from the overhead pulleys, a pulley on the tool shaft about which the belt next passes, and a weight riding upon the beltbetween the overhead pulleys and the tool shaft, substantially asdescribed.

3. In a dental engine, a tool shaft mounted upon a standard which isadapted to be arranged upon a vertically adjustable operating chair, abelt passing about a driven wheel, overhead twin pulleys about which thebelt thence passes, twin pulleys arranged in a loose collar on thestandard below the tool shaft and receiving the belt from the overheadpulleys, a pulley on the tool shaft about which the belt next passes,and a weight riding upon the belt between the overhead pulleys and thetool shaft, substantially as described.

4:. In a dental engine, a tool shaft mounted upon a standard which isadapted to be arranged upon a vertically adjustable operating chair, abelt passing about a driven wheel, overhead twin pulleys about which thebelt thence passes, twin pulleys arranged below the tool shaft andreceiving the belt from the overhead pulleys, a pulley on the tool shaftabout which the belt next passes, and a weight riding upon the beltbetween the overhead pulleys and the tool shaft, combined with anindependent tension-relieving device applied 6 5 to the pulleys belowthe tool shaft, substantially as described.

Signed at New York, in the county of New York and State of New York.

RUFUS G. S'IANBROUGII.

\Vi tnesses:

Fnnnnmo CARRAGAN, EUGENE V. M'vnns.

